A subterranean well typically includes various pieces of electrical equipment (e.g., an electrical submersible pump, well telemetry tool, and other electrical powered devices) that are located downhole within the well or beneath the surface of the sea adjacent to the well. For purposes of providing power to operate such electrical equipment, electrical cables may be run from a surface power source to the subsea equipment to establish an umbilical connection. Some conventional subsea power sources employ traditional surface techniques with minimized facilities. An example of this approach is the use of a surface buoy with a diesel generator within. Alternatively, a power source may be placed on or near the seabed proximate the electrical equipment and electrical cables may be run between the power supply and the equipment.
However, it is often not practical to use electrical cables running from the surface or seabed to the subterranean or subsea site of the electrically-powered device, because of the great distance involved, or because the cables can interfere with the passage of other equipment through the wellbore, and are vulnerable to being damaged during well operations. Moreover, conventional power generators or power sources do not provide self-sustaining systems. Thus, as soon as the primary power supply is removed, the output of work or operations is stopped.
Accordingly, there exists a need for a self-sustaining subsea power supply system for use in powering subsea well operations, which generates power from waste or free energy (e.g., wind, solar, thermal, wave, pressurized subsurface gases and liquids, and so forth) without cost to directly provide a fuel and/or electricity.